The present invention relates to hand tools particularly to an adjustable wrench adapted to set and loose. The jaw unit thread connection assembly, which comprises a worm gear rack mechanism with a clutch unit, and a movable jaw unit which has a smooth lateral side and a toothed lateral side which can be removed from the wrench body, turned over and then inserted back, thereby alternating the functions of the wrench as a normal wrench or as a pipe wrench which is to set or loosen a pipe thread connection.
It is well known that the opening of a prior adjustable wrench is adjusted by means of worm gear rack mechanism. A quickly adjustable wrench has been disclosed, in which the quick adjustment is obtained by pushing the worm away from the engagement with the gear rack of the movable jaw. However, the above adjustable wrench has been found to have poor reliability, firmness and mechanical strength resulting from unsteady position of the worm in the worm gear rack mechanism. Moreover, the prior wrench has another disadvantage that it is only adapted to effectively function either as a normal adjustable wrench to deal with a bolt connection or as a pipe wrench to deal with pipe thread connection and is not able to effectively deal with above two connections at the same time.
Accordingly, the object of the invention is to provide a dual-purpose quickly adjustable wrench with perfect reliability, firmness and mechanical strength. The opening of the wrench can be quickly adjusted and the functions of the wrench can be alternated conveniently by means of a clutch unit to control the worm gear rack mechanism, a shaft of the worm fixed when the worm is in the position of engagement, and a movable jaw unit which has a smooth lateral side and a toothed lateral side.